1. Field of the Invention
The present invention relates to a developing device that is attachable to and detachable from a developer supplying device provided in a body of an image forming apparatus. Specifically, the present invention relates to a shutter mechanism that opens and shuts a developer receiving port that receives developer supplied from the developer supplying device.
2. Description of the Related Art
There are known image forming apparatuses including developing devices and developer supplying devices. The developing devices each develop an electrostatic image formed on a photoconductive drum into a toner image with, for example, a two-component developer composed of a toner and a magnetic carrier. The developer supplying devices each supply the developer to the developing device. The developing device is provided either as a sole component or as a unit called process cartridge including other associated image forming elements (such as a photoconductor drum), and is detachably attached to the body of the image forming apparatus. The process cartridge (the developing device) is connected to the developer supplying device provided in the body of the image forming apparatus. In the body of the image forming apparatus, a developer receiving port provided in the process cartridge communicates with a developer supply port provided in the developer supplying device.
Such an image forming apparatus includes a shutter mechanism that opens and shuts the developer supply port in conjunction with the attaching or detaching of the process cartridge so that the developer does not leak from the developer supply port of the developer supplying device when the process cartridge is attached to or detached from the body of the image forming apparatus (see Japanese Patent Laid-Open No. 2012-108457).
Another known process cartridge includes a shutter mechanism that opens and shuts a developer receiving port of a developing device (see Japanese Patent Laid-Open No. 2012-8457). In this shutter mechanism, when the image forming apparatus is powered for the first time, a shutter that has been at a position for shutting the developer receiving port is slid to a position for opening the developer receiving port in accordance with the rotation of a stirring member provided in a developer container.
Process cartridges (developing devices), which are consumables, are each shipped while being set in the body of an image forming apparatus. In the case of the shutter mechanism disclosed by Japanese Patent Laid-Open No. 2012-108457, a gap tends to be produced at the connection between the developer supply port and the developer receiving port because of vibrations, impacts, or the like that may be applied to the process cartridge during transportation, installation, or the like. In such a case, the developer may leak from the gap.
In the case of the shutter mechanism disclosed by Japanese Patent Laid-Open No. 2012-8457, the above leakage of the developer from the connection between the developer supply port and the developer receiving port is not likely to occur. However, this shutter mechanism requires a large torque out of the necessity of not only stirring and conveying the developer but also moving the shutter, and therefore requires a high-performance motor. Moreover, the shutter mechanism has a complicated configuration with an increased number of components. Because of this, a process cartridge including a shutter mechanism as described, has high costs despite being a consumable.